In the 3rd Generation Partnership Project (3GPP) standardization body technologies like Global System for Mobile Communication (GSM), High-Speed Packet Access (HSPA) and Long Term Evolution (LTE) have been and are currently developed.
LTE is the latest technology standardised. It uses an access technology based on OFDM (Orthogonal Frequency Division Multiplexing) for the downlink (DL) and Single Carrier FDMA (SC-FDMA) for the uplink (UL). The resource allocation to mobile stations, in LTE denoted user equipment (UE), on both DL and UL is performed adaptively by the concept of fast scheduling, taking into account the instantaneous traffic pattern and radio propagation characteristics of each mobile station. Assigning resources in both DL and UL is performed in a so-called scheduler situated in a base station, in LTE often denoted eNodeB.
In e.g. LTE, uplink transmissions are scheduled by a base station. A grant is transmitted on the downlink control channel PDCCH and the mobile station responds with a transmission using the resources specified in the grant and with the size specified in the grant. The mobile station can let the base station know that it wants to transmit by sending a scheduling request (SR) on the uplink control channel PUCCH at predefined times. Typically the mobile station transmits an SR which is followed by one or many grants, each resulting in one uplink transmission. This is commonly referred to as dynamic scheduling.
With the higher speeds a number of various applications that a user of the mobile station can be engaged in have evolved. It is for instance of interest for a user to involve him- or herself in online games, where small amounts of uplink data are transferred fairly often from the mobile station to another device involved in a game. Here the transferred data may be gaming commands and the other device may be another mobile station or another type of user terminal like a PC or even a server. Gaming is one example of delay-sensitive traffic. The increase of this delay-sensitive traffic and its significant share in the internet traffic leads to the radio interfaces of wireless communication systems having to meet various latency requirements to ensure that a mobile station user can enjoy the activities employing this type of traffic. Another example of delay-sensitive traffic is ping. Ping is for instance used to estimate the delay of a channel as well as to measure the performance in radio systems in order to for instance compare and/or rank different systems.
Setting up of traffic in a wireless communication network is often referred as allocation of resources. When resources are allocated to a mobile station desiring to send data in the uplink, there are normally a number of activities that have to be performed. First the mobile station sends a scheduling request (SR). This is followed by the base station responding with a grant, which grant includes information on what time/frequency resources the mobile station shall use. The mobile station then transfers a Buffer Status Report (BSR) after which the base station issues a grant for further data. It is not until it receives this further grant that the mobile station can transmit the actual data it intends. This process is time consuming, especially if the mobile station is to run through the process each time it desires to transfer data.
It is not required that an SR precedes the grant. When the base station knows that a mobile has a periodic service or for some other reason can predict future data arrivals it can transmit a grant to the mobile without waiting for an SR. It is also possible to blindly transmit grants in order to speed up the scheduling. These scheduling methods are called predictive scheduling.
However, predictive scheduling may cause so called padding transmissions from a mobile station if the mobile does not have data in the buffer. Padding transmissions are messages containing no relevant information, and should thus be avoided as much as possible.
There is in view of what has been described above a need for avoiding the sending of transmissions comprising only padding for a mobile station provided with predictive scheduling.